The site has put together a truly useful diagram that cuts through the hype of mobile payments, and it delivers some useful projections to keep in mind as well. With the mobile payments market set to explode — Juniper predicts it will reach $670 billion by 2015, while Yankee Group thinks it could hit $1 trillion — it’s worth knowing exactly where different offerings lie.

As the graphic shows, there are five main types of mobile payments. The two we hear the most about are mobile payments at the point of sale, like Google Wallet and Isis, and mobile payments as the point of sale, like Square and Intuit’s GoPayment. NFC, or near-field communications, is just one of many ways mobile devices (and even credit cards) can take advantage of these two mobile payment types.

Then there are mobile payment platforms, like PayPal’s many mobile initiatives, that cover just about everything else you do with money on mobile devices, like sending money to friends or even merchants. According to the graphic: “It might be at the point of sale. It might be online. It might use text messages or even NFC someday.”

The other two mobile payment categories include direct carrier billing, which charge digital purchases to your cellphone bill (like Boku, or PayPal-owned Zong), and closed loop mobile payments, wherein a company builds a payment infrastructure for its own use. Starbucks has found success with the latter using its mobile apps, which processed 3 million transactions in its first two months available.